/*
 *                               POK header
 *
 * The following file is a part of the POK project. Any modification should
 * be made according to the POK licence. You CANNOT use this file or a part
 * of a file for your own project.
 *
 * For more information on the POK licence, please see our LICENCE FILE
 *
 * Please follow the coding guidelines described in doc/CODING_GUIDELINES
 *
 *                                      Copyright (c) 2007-2021 POK team
 */

/* e_lgammaf_r.c -- float version of e_lgamma_r.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#ifdef POK_NEEDS_LIBMATH

#include "math_private.h"
#include <libm.h>

static const float two23 = 8.3886080000e+06, /* 0x4b000000 */
    half = 5.0000000000e-01,                 /* 0x3f000000 */
    one = 1.0000000000e+00,                  /* 0x3f800000 */
    pi = 3.1415927410e+00,                   /* 0x40490fdb */
    a0 = 7.7215664089e-02,                   /* 0x3d9e233f */
    a1 = 3.2246702909e-01,                   /* 0x3ea51a66 */
    a2 = 6.7352302372e-02,                   /* 0x3d89f001 */
    a3 = 2.0580807701e-02,                   /* 0x3ca89915 */
    a4 = 7.3855509982e-03,                   /* 0x3bf2027e */
    a5 = 2.8905137442e-03,                   /* 0x3b3d6ec6 */
    a6 = 1.1927076848e-03,                   /* 0x3a9c54a1 */
    a7 = 5.1006977446e-04,                   /* 0x3a05b634 */
    a8 = 2.2086278477e-04,                   /* 0x39679767 */
    a9 = 1.0801156895e-04,                   /* 0x38e28445 */
    a10 = 2.5214456400e-05,                  /* 0x37d383a2 */
    a11 = 4.4864096708e-05,                  /* 0x383c2c75 */
    tc = 1.4616321325e+00,                   /* 0x3fbb16c3 */
    tf = -1.2148628384e-01,                  /* 0xbdf8cdcd */
    /* tt = -(tail of tf) */
    tt = 6.6971006518e-09,   /* 0x31e61c52 */
    t0 = 4.8383611441e-01,   /* 0x3ef7b95e */
    t1 = -1.4758771658e-01,  /* 0xbe17213c */
    t2 = 6.4624942839e-02,   /* 0x3d845a15 */
    t3 = -3.2788541168e-02,  /* 0xbd064d47 */
    t4 = 1.7970675603e-02,   /* 0x3c93373d */
    t5 = -1.0314224288e-02,  /* 0xbc28fcfe */
    t6 = 6.1005386524e-03,   /* 0x3bc7e707 */
    t7 = -3.6845202558e-03,  /* 0xbb7177fe */
    t8 = 2.2596477065e-03,   /* 0x3b141699 */
    t9 = -1.4034647029e-03,  /* 0xbab7f476 */
    t10 = 8.8108185446e-04,  /* 0x3a66f867 */
    t11 = -5.3859531181e-04, /* 0xba0d3085 */
    t12 = 3.1563205994e-04,  /* 0x39a57b6b */
    t13 = -3.1275415677e-04, /* 0xb9a3f927 */
    t14 = 3.3552918467e-04,  /* 0x39afe9f7 */
    u0 = -7.7215664089e-02,  /* 0xbd9e233f */
    u1 = 6.3282704353e-01,   /* 0x3f2200f4 */
    u2 = 1.4549225569e+00,   /* 0x3fba3ae7 */
    u3 = 9.7771751881e-01,   /* 0x3f7a4bb2 */
    u4 = 2.2896373272e-01,   /* 0x3e6a7578 */
    u5 = 1.3381091878e-02,   /* 0x3c5b3c5e */
    v1 = 2.4559779167e+00,   /* 0x401d2ebe */
    v2 = 2.1284897327e+00,   /* 0x4008392d */
    v3 = 7.6928514242e-01,   /* 0x3f44efdf */
    v4 = 1.0422264785e-01,   /* 0x3dd572af */
    v5 = 3.2170924824e-03,   /* 0x3b52d5db */
    s0 = -7.7215664089e-02,  /* 0xbd9e233f */
    s1 = 2.1498242021e-01,   /* 0x3e5c245a */
    s2 = 3.2577878237e-01,   /* 0x3ea6cc7a */
    s3 = 1.4635047317e-01,   /* 0x3e15dce6 */
    s4 = 2.6642270386e-02,   /* 0x3cda40e4 */
    s5 = 1.8402845599e-03,   /* 0x3af135b4 */
    s6 = 3.1947532989e-05,   /* 0x3805ff67 */
    r1 = 1.3920053244e+00,   /* 0x3fb22d3b */
    r2 = 7.2193557024e-01,   /* 0x3f38d0c5 */
    r3 = 1.7193385959e-01,   /* 0x3e300f6e */
    r4 = 1.8645919859e-02,   /* 0x3c98bf54 */
    r5 = 7.7794247773e-04,   /* 0x3a4beed6 */
    r6 = 7.3266842264e-06,   /* 0x36f5d7bd */
    w0 = 4.1893854737e-01,   /* 0x3ed67f1d */
    w1 = 8.3333335817e-02,   /* 0x3daaaaab */
    w2 = -2.7777778450e-03,  /* 0xbb360b61 */
    w3 = 7.9365057172e-04,   /* 0x3a500cfd */
    w4 = -5.9518753551e-04,  /* 0xba1c065c */
    w5 = 8.3633989561e-04,   /* 0x3a5b3dd2 */
    w6 = -1.6309292987e-03;  /* 0xbad5c4e8 */

static const float zero = 0.0000000000e+00;

static float sin_pif(float x) {
  float y, z;
  int n, ix;

  GET_FLOAT_WORD(ix, x);
  ix &= 0x7fffffff;

  if (ix < 0x3e800000)
    return __kernel_sinf(pi * x, zero, 0);
  y = -x; /* x is assume negative */

  /*
   * argument reduction, make sure inexact flag not raised if input
   * is an integer
   */
  z = floorf(y);
  if (z != y) { /* inexact anyway */
    y *= (float)0.5;
    y = (float)2.0 * (y - floorf(y)); /* y = |x| mod 2.0 */
    n = (int)(y * (float)4.0);
  } else {
    if (ix >= 0x4b800000) {
      y = zero;
      n = 0; /* y must be even */
    } else {
      if (ix < 0x4b000000)
        z = y + two23; /* exact */
      GET_FLOAT_WORD(n, z);
      n &= 1;
      y = n;
      n <<= 2;
    }
  }
  switch (n) {
  case 0:
    y = __kernel_sinf(pi * y, zero, 0);
    break;
  case 1:
  case 2:
    y = __kernel_cosf(pi * ((float)0.5 - y), zero);
    break;
  case 3:
  case 4:
    y = __kernel_sinf(pi * (one - y), zero, 0);
    break;
  case 5:
  case 6:
    y = -__kernel_cosf(pi * (y - (float)1.5), zero);
    break;
  default:
    y = __kernel_sinf(pi * (y - (float)2.0), zero, 0);
    break;
  }
  return -y;
}

float __ieee754_lgammaf_r(float x, int *signgamp) {
  float t, y, z, nadj, p, p1, p2, p3, q, r, w;
  int i, hx, ix;

  nadj = 0;
  GET_FLOAT_WORD(hx, x);

  /* purge off +-inf, NaN, +-0, and negative arguments */
  *signgamp = 1;
  ix = hx & 0x7fffffff;
  if (ix >= 0x7f800000)
    return x * x;
  if (ix == 0)
    return one / zero;
  if (ix < 0x1c800000) { /* |x|<2**-70, return -log(|x|) */
    if (hx < 0) {
      *signgamp = -1;
      return -__ieee754_logf(-x);
    } else
      return -__ieee754_logf(x);
  }
  if (hx < 0) {
    if (ix >= 0x4b000000) /* |x|>=2**23, must be -integer */
      return one / zero;
    t = sin_pif(x);
    if (t == zero)
      return one / zero; /* -integer */
    nadj = __ieee754_logf(pi / fabsf(t * x));
    if (t < zero)
      *signgamp = -1;
    x = -x;
  }

  /* purge off 1 and 2 */
  if (ix == 0x3f800000 || ix == 0x40000000)
    r = 0;
  /* for x < 2.0 */
  else if (ix < 0x40000000) {
    if (ix <= 0x3f666666) { /* lgamma(x) = lgamma(x+1)-log(x) */
      r = -__ieee754_logf(x);
      if (ix >= 0x3f3b4a20) {
        y = one - x;
        i = 0;
      } else if (ix >= 0x3e6d3308) {
        y = x - (tc - one);
        i = 1;
      } else {
        y = x;
        i = 2;
      }
    } else {
      r = zero;
      if (ix >= 0x3fdda618) {
        y = (float)2.0 - x;
        i = 0;
      } /* [1.7316,2] */
      else if (ix >= 0x3F9da620) {
        y = x - tc;
        i = 1;
      } /* [1.23,1.73] */
      else {
        y = x - one;
        i = 2;
      }
    }
    switch (i) {
    case 0:
      z = y * y;
      p1 = a0 + z * (a2 + z * (a4 + z * (a6 + z * (a8 + z * a10))));
      p2 = z * (a1 + z * (a3 + z * (a5 + z * (a7 + z * (a9 + z * a11)))));
      p = y * p1 + p2;
      r += (p - (float)0.5 * y);
      break;
    case 1:
      z = y * y;
      w = z * y;
      p1 = t0 + w * (t3 + w * (t6 + w * (t9 + w * t12))); /* parallel comp */
      p2 = t1 + w * (t4 + w * (t7 + w * (t10 + w * t13)));
      p3 = t2 + w * (t5 + w * (t8 + w * (t11 + w * t14)));
      p = z * p1 - (tt - w * (p2 + y * p3));
      r += (tf + p);
      break;
    case 2:
      p1 = y * (u0 + y * (u1 + y * (u2 + y * (u3 + y * (u4 + y * u5)))));
      p2 = one + y * (v1 + y * (v2 + y * (v3 + y * (v4 + y * v5))));
      r += (-(float)0.5 * y + p1 / p2);
    }
  } else if (ix < 0x41000000) { /* x < 8.0 */
    i = (int)x;
    t = zero;
    y = x - (float)i;
    p = y *
        (s0 + y * (s1 + y * (s2 + y * (s3 + y * (s4 + y * (s5 + y * s6))))));
    q = one + y * (r1 + y * (r2 + y * (r3 + y * (r4 + y * (r5 + y * r6)))));
    r = half * y + p / q;
    z = one; /* lgamma(1+s) = log(s) + lgamma(s) */
    switch (i) {
    case 7:
      z *= (y + (float)6.0); /* FALLTHRU */
    case 6:
      z *= (y + (float)5.0); /* FALLTHRU */
    case 5:
      z *= (y + (float)4.0); /* FALLTHRU */
    case 4:
      z *= (y + (float)3.0); /* FALLTHRU */
    case 3:
      z *= (y + (float)2.0); /* FALLTHRU */
      r += __ieee754_logf(z);
      break;
    }
    /* 8.0 <= x < 2**58 */
  } else if (ix < 0x5c800000) {
    t = __ieee754_logf(x);
    z = one / x;
    y = z * z;
    w = w0 + z * (w1 + y * (w2 + y * (w3 + y * (w4 + y * (w5 + y * w6)))));
    r = (x - half) * (t - one) + w;
  } else
    /* 2**58 <= x <= inf */
    r = x * (__ieee754_logf(x) - one);
  if (hx < 0)
    r = nadj - r;
  return r;
}

#endif
